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Full text of "Text Book Of Mechanical Engineering"

326

Tube Beader, Cutter> &c.

Yarrow recommends the roller shewn at #, and advises that the
hole in the tube plate should be rimered to the same taper as
the mandrel F.

1 Tube Beader (Fig. 305).H is the body of the tool, con-
taining three jaws at j capable of sliding radially, and moved out-
ward by the taper part of bolt K when nut L is tightened up.
This is done when the beader is put in place, the disc M serving as
steadiment. The collar N holds three rollers, placed at such an
angle as to do the work efficiently, and a ratchet wheel o is keyed
to N. P is the feed nut, and the ratchet arm Q rides loosely on N,
the latter being driven by Q, like the drill in Fig. 215. But there
is one depression b in the rim of the feed nut P, so that when Q
has, by its vibrations, brought N round by one revolution, the feed
nut is automatically advanced by a small amount. The firebox
ends of the tubes being excessively strained by the great variations
in temperature there occurring, beading protects the joint, while
the ferrule R, in addition, secures the rigidity not obtainable by
simple expanding.

* Tube, Gutter.As it is impossible to gauge the length of
the tubes accurately beforehand, the tool at Fig. 306 becomes
necessary. Three bearings s s s, capable of radial sliding, support
hard steel discs x x x, which are the cutters. The tapered bolt u
advances these bearings outwardly when tightened up by the
nut v; this may be termed the feed. The tool body w has a
square at x and an adjustable gauge at z, b.y which tjie cutters
are set. The gauge being fixed, the tool inserted, and nut v
screwed up, a spanner on x rotafes the whole. Then v is
tightened, the operation repeated, and so on till the tube is cut
through.

4 Ferrule Extractor.As tubes have to be withdrawn and
replaced, and .the ferrule is the most troublesome portion to
remove, the extractor at Fig. 307 has been contrived to meet this
difficulty. The washer b is first placed against the tube plate;
then the set screw d released to allow the jaws ef to enter.
When all are in position the screw d is advanced to press the
jaws against the tube, and the nut g then tightened with a long
spanner ^nd the ferrule drawn out All the four foregoing tools
are supplied by Messrs. Selig, Sonnenthal & Co. *



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